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TLS Online TPP Program

#Question id: 1513

The kinase activity of ATM is activated in response to DNA damage due to various stresses (e.g., UV irradiation, heat). Activated ATM then triggers following pathways leading to arrest in G1.

A. Chk2 is phosphorylated and, in turn, phosphorylates Cdc25A, thereby marking it for degradation and blocking its role in CDK2 activation.

B. Phosphorylation of p53 stabilizes it, permitting p53-activated expression of genes encoding proteins that cause arrest in G1, promote apoptosis, or participate in DNA repair.

C. Controlling the pool of p53, ATM phosphorylates MDM2 to inactivate it, causing increased stabilization of p53. Another protein p14ARF inhibits the activity of Mdm2 thus stabilizing p53.

Based on the above information, which one of the following statements is correct?

#Unit 4. Cell Communication and Cell Signaling

  1. Gain-of-function of p14ARF and Loss-of-function of p53 leads to tumor formation.

  2. Gain-of-function of p53 and Loss-of-function of Chk2 leads to tumor formation.

  3. Gain-of-function of Cdc25A and Loss-of-function of Chk2 leads to tumor formation.

  4. Gain-of-function of Chk2 and Loss-of-function of MDM2 leads to tumor formation.

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TLS Online TPP Program

#Question id: 24576

#Unit 10. Ecological Principles

The birth of 100 cockroaches to a population of 1,000 would represent a birth rate. Similarly, the death of 50 cockroaches in a population of 1,000 would be a death rate, d, per individual per week. Calculate the rate of change in a population per unit time ?
TLS Online TPP Program

#Question id: 27374

#Unit 13. Methods in Biology

An aqueous solution contains two compounds X and Y. This solution gave absorbance values of 1.0 and 0.4 at 220 and 280 nm, respectively, in a 1 cm path length cell. Molar absorption coefficients (ε) of the compounds X and Y are as shown in the table below.

The concentration of Y in the solution is___________ mM.
TLS Online TPP Program

#Question id: 8968

#Unit 9. Diversity of Life Forms

Which of the following statements concerning animal taxonomy is (are) true?
1. Animals are more closely related to plants than to fungi.
2. All animal clades based on body plan have been found to be incorrect.
3. Kingdom Animalia is monophyletic.
4. Only animals reproduce by sexual means.
5. Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.
TLS Online TPP Program

#Question id: 19733

#Unit 3. Fundamental Processes

Extensive shortening of telomeres eventually leads to 
TLS Online TPP Program

#Question id: 19045

#Unit 13. Methods in Biology

The process of passing a mobile phase through a chromatography column is called which one of the following?